I have the same problem, niether weylin nor the woman he's attempting to kill can die. I've tried loading a previous save and using loot and it hasn't worked. Kill comands do nothing and markfordelete only deletes the physical entity of weylin, his image remains frozen in place

Yup, does nothing. In fact they aren't essential characters anyway, essential characters are incapacitated and you can't finish them. These two die for a nanosecond then instantly have full health again and it's as if they didn't die.

I had this same issue, do you have the Run for Your Lives or When Vampires attack mod? I fixed this by disabling those mods and loading a save outside of Markarth. When you go back to Markarth, Weylin should kill Margret and the quest should continue like normal.

I had this same issue, do you have the Run for Your Lives or When Vampires attack mod? I fixed this by disabling those mods and loading a save outside of Markarth. When you go back to Markarth, Weylin should kill Margret and the quest should continue like normal.

Sounds even more like a load order issue, or some other bugged mod. I have both of those mods that you mentiond and I am able to kill Weylin, when entering the city.

Regardless of load orders, i just tried deactivating run for your lives and it fixed the quest instantly. Thanks for the fix

That is interesting to know. If there is something in that mod interfering with Weylin's AI, then it obviously does not affect to us all.

Those that have been affected by it might wish to inform Arthmoor about it. It really doesn't help, if someone without this bug (like me) would start reporting about it, because I could not answer to any questions about possible common traits and mods among players that have this problem.

Drop the line in to Posts -section (sticky post has intructions), or PM Arhmoor about it. There is no reason to let this bug spread.

I had this same issue, do you have the Run for Your Lives or When Vampires attack mod? I fixed this by disabling those mods and loading a save outside of Markarth. When you go back to Markarth, Weylin should kill Margret and the quest should continue like normal.